Portion of a shoe midsole



FIG. 1 is a side view of a portion of a shoe midsole showing our design.

The uneven broken lines immediately adjacent to the pair of generally quadrilaterally-shaped features represent unclaimed boundaries of the design. The uneven broken line showing of the remainder of the shoe is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a portion of a shoe midsole, as shown and described. 